The demonstration of chemical experiments to large audiences has been somewhat difficult in the past because, generally, such demonstrations either required the observers present to be close to the experiment, and hence the laboratory table and apparatus, or required a video transmission of the experiment to monitors which could be conveniently viewed by the individuals. Opaque projectors, overhead projectors and other apparatus, of course, have increased the ability of large numbers of observers to simultaneously view a display and indeed, such techniques have been employed for demonstrating chemical reactions within certain limits.
Because of the nature of these projectors, it has been necessary to carry out the reaction in a flat form or in a horizontal orientation of the vessel and this has, as a practical matter, limited the utility of the apparatus to the display of chemical and other reactions in watch glasses, petri dishes, crystallizing dishes and the like.
As a consequence, the types of experiments which could be carried out and displayed by projection have also been limited to those which could be carried out in such vessels and under these circumstances.
In the German Democratic Republic Patent No. WP 99,467, there is described the so-called polylux universal cuvette which has a special holder enabling it to be oriented at an angle of 22.degree. for the display of chemical experiments and, while this has certainly broadened the field of chemical experiments which could be demonstrated utilizing projectors, it nevertheless was not fully satisfactory because the manipulation of this cuvette was complicated and it also had only limited utility.
It has been proposed to provide a vertical stage as an appropriate display, but here the projector had to be equipped with light-deflecting mirrors and tilting devices and for the most part, these vertical stages could be utilized only for the display of experiments in conventional apparatus as shadow images rather than true transluminations. In these systems, for example, the plane parallel surfaces required for true translumination for contrast images were not available.
Physics demonstrations and demonstrations of mechanical principles have been made effectively using cuvettes in the so-called diapanel system in which between the walls of the diapanel, physical actions could be demonstrated, e.g. those of a pump. For demonstration of chemical experiments, however, such systems were not suitable, at least in part because chemical experiments generally require more than one active space or compartment, and systems having more than one compartment were not available in the diapanels of the prior art.
In general, therefore, it can be said that school demonstration experiments, experiments on a semimicro basis for analytic, preparative, scientific and technological purposes in short time periods with small amounts of substances could not be effected in a manner enabling their display to large numbers of individuals utilizing conventional projecting equipment.